<?php

$funArray = array('sum','mul','div','sub');
shuffle($funArray);
echo $function = array_shift($funArray);
echo $function(20,4);
echo "\n";

function sum($a,$b)
{
  return ($a+$b);
}

function mul($a,$b)
{
  return ($a*$b);
}

function div($a,$b)
{
  return ($a/$b);
}

function sub($a,$b)
{
  return ($a-$b);
}
